What do unbalanced forces result in?

Unbalanced forces lead to a change in an object's motion, which is rooted in Newton's second law of motion. When forces acting on an object are not equal in size or opposite in direction, they create a net force. This net force causes the object to accelerate in the direction of the greater force, resulting in a change in its velocity. This change could manifest as an increase or decrease in speed, or a change in direction, which is why unbalanced forces are fundamental to understanding how objects move in response to the forces acting upon them.

In contrast, when forces are balanced, they result in no net force acting on the object, leading to no change in movement (the first option). If an object is already in motion with balanced forces, it will continue at a constant speed without accelerating or changing direction (the second option). While unbalanced forces can lead to changes in motion, they are not directly related to friction being reduced (the fourth option), as friction is a separate factor that opposes motion. Thus, the correct answer identifies the direct consequence of unbalanced forces acting on an object.